Stronger units, wracks incubi etc have a much better chance of surviving an exploding raider and as such can be used differently. Here I am speaking mostly of raiders attached to Warriors and Wyches.
I use a Raider for really only two things,
1. Transports: Getting your units where you can use them. Raiders are excellent for this, they are fast and open topped. Meaning I can fleet and assault out of each vehicle, giving me incredible assault ranges, and or rapid fire or blaster range. A raider takes a 18" blaster and turns it into a 33" shot.
Raiders go down fast, even in waves. Get what you can out of them.